1. Field of Invention
This invention relates to the field of object illumination rendering.
2. Background of the Invention
The realism of rendered graphics of an object often depends on the accuracy of the illumination effects associated with the object that is being modeled. These illumination effects typically require intensive processing, especially for real-time graphics rendering. Many of the available rendering methods, however, do not effectively account for illumination effects. For a non-limiting example, some low-order methods for calculating the illumination effects only use a limited number of lighting coefficients and thus are limited to low-frequency lighting and produce only soft shadows for the rendered object.
Recent computer graphics research has explored the use of spherical harmonics (SH) for global illumination to generate realistic real-time rendering of 3D scenes of an object, taking into account subtle effects through different types of diffuse lighting models, which include but are not limited to, un-shadowed, shadowed, and inter-reflected. The goal is to render the global illumination of the object lit by any type of light sources. The lighting environment and the local visibility of the object can be independently pre-computed as SH coefficients thus permitting near-instantaneous relighting of objects. However, the pre-computation of the SH coefficients is often quite expensive in terms of computing resources consumed.